Binary star system in Pismis 24, Hubble Space Telescope image. This binary star system was discovered using Hubble's powerful visual resolution. Previously, it was thought that this was a single star, which would have been beyond the theoretical mass limit for star formation. It is the largest and brightest member of a star cluster in NGC 6357 (see R560/444). This binary system is known as Pismis 24-1. It is now thought that it may in fact be a triple system, with another star that even Hubble cannot see. This binary star system is 8000 light years from Earth, in the constellation Scorpius. This image was obtained with Hubble's Advanced Camera for Surveys instrument. The results were published in December 2006.